0:00:06 > 0:00:10It's a physical quest, it's a spiritual quest,
0:00:10 > 0:00:14it's a reach out there for what our place is in the universe.
0:00:14 > 0:00:17When I joined NASA, I was going to Mars.
0:00:17 > 0:00:21I was not just dreaming, I was going to Mars.
0:00:41 > 0:00:45Mars has captured our imagination more than any other planet, and that's for one reason above all -
0:00:45 > 0:00:49the hope, the possibility that there may be life on Mars.
0:00:49 > 0:00:53This idea is so enticing that we've long wanted to go there.
0:00:53 > 0:00:56We've even imagine Martians coming to earth and invading us.
0:00:56 > 0:00:59For 40 years, we've been able to address the question
0:00:59 > 0:01:02of whether or not there's life on Mars through science,
0:01:02 > 0:01:05and the BBC has been there for every revelation.
0:01:05 > 0:01:09From the first tantalising images of the surface...
0:01:09 > 0:01:11We've just had some amazing photographs sent back
0:01:11 > 0:01:14by the American probe to Mars, Mariner 6.
0:01:14 > 0:01:17You can see there some of the dark areas, which may be vegetation,
0:01:17 > 0:01:20and at the bottom you can see the white polar cap, which has always
0:01:20 > 0:01:24been thought to be due to some kind of icy or frosty deposit.
0:01:25 > 0:01:28..to the excitements of a successful landing.
0:01:28 > 0:01:32The stakes are high when only half of missions make it.
0:01:35 > 0:01:40Now it looks after all as if the Beagle may have crash-landed.
0:01:40 > 0:01:43When the first evidence of life on Mars filled our screens,
0:01:43 > 0:01:46it seemed possible that we were no longer alone in the universe.
0:01:46 > 0:01:48It had 10 to 12 segments in it
0:01:48 > 0:01:53and appeared to have a head and appeared to have a tail.
0:01:53 > 0:01:57Horizon and the BBC have followed the hopes and dreams of astronomers
0:01:57 > 0:02:00as they explore the red planet and its mysteries,
0:02:00 > 0:02:04and bring us closer than ever to finding life on Mars.
0:02:17 > 0:02:21Mars is the planet in our solar system that's most like Earth.
0:02:21 > 0:02:26It has days and seasons. It's covered in valleys and volcanoes.
0:02:26 > 0:02:30There's even evidence that water once flowed across the surface.
0:02:30 > 0:02:32We've seen it up close, in photographs,
0:02:32 > 0:02:34and decades of exploration
0:02:34 > 0:02:36means we now understand much
0:02:36 > 0:02:40about the geology, atmosphere and geography of the Red Planet.
0:02:40 > 0:02:42But our fascination with it
0:02:42 > 0:02:46really comes down to the one question that remains unanswered.
0:02:46 > 0:02:50If Mars is like Earth, then has there ever been life on Mars too?
0:02:56 > 0:03:00Finding evidence of life on Mars is a tantalising prospect for us all.
0:03:00 > 0:03:04Proof would show that this is not a miracle unique to Earth.
0:03:04 > 0:03:09And if it happened twice in our solar system then the universe must be teeming with life.
0:03:11 > 0:03:17The idea of life on Mars is as old as the observatories themselves.
0:03:17 > 0:03:20By the late 1800s, telescopes have become powerful enough
0:03:20 > 0:03:23for astronomers to map the surface of Mars.
0:03:24 > 0:03:27They observed light and dark patches
0:03:27 > 0:03:29and thought these could be seas and forests.
0:03:30 > 0:03:34Some astronomers, like Percival Lowell, even believed that
0:03:34 > 0:03:38they'd seen canals on the surface, built by intelligent life.
0:03:38 > 0:03:41That Mars is inhabited by beings of some sort or other
0:03:41 > 0:03:47we may consider as certain as it is uncertain what those beings may be.
0:03:48 > 0:03:52From childhood, we have been fascinated by what Martian life might look like.
0:03:52 > 0:03:54DISTORTED ROAR
0:03:54 > 0:03:58Something is happening to the children of Mars.
0:03:58 > 0:04:02Timar, as leader of the Martians you must do something about it.
0:04:04 > 0:04:06I know. But what?
0:04:16 > 0:04:21Astronomers at NASA also imagined what life on the Red Planet might be like.
0:04:21 > 0:04:25But once they applied science their ideas were quite different.
0:04:25 > 0:04:29On Mars, deadly ultraviolet radiation from the sun
0:04:29 > 0:04:32penetrates to the surface.
0:04:32 > 0:04:34Life forms on Mars may have silica shells
0:04:34 > 0:04:37to protect them against this radiation.
0:04:37 > 0:04:40We know that Mars is very dry.
0:04:40 > 0:04:46Life forms on Mars may have developed special ways of preserving their water content.
0:04:46 > 0:04:49There may be a kind of plant, an ice-eater,
0:04:49 > 0:04:52with fine, root-like probes,
0:04:52 > 0:04:54searching, not for liquid water,
0:04:54 > 0:04:59but searching the permafrost, reaching down to get at that ice.
0:04:59 > 0:05:02For Horizon, these imaginings were a step too far.
0:05:02 > 0:05:06Other scientists had something smaller in mind.
0:05:06 > 0:05:08The biologists were more sceptical.
0:05:08 > 0:05:11But they'd already begun to design experiments to test the possibility
0:05:11 > 0:05:15that micro-organisms may have survived on Mars.
0:05:17 > 0:05:22One theory was that they were dormant and that a cocktail of nutrients would awaken them into life.
0:05:27 > 0:05:31Another experiment did imagine that plant-like cells
0:05:31 > 0:05:34had adapted to the harsh ultraviolet light on the planet
0:05:34 > 0:05:36and might still survive.
0:05:37 > 0:05:41But even these ideas about life on Mars were guesswork.
0:05:41 > 0:05:46To truly understand what it might be like, we needed to find out more about the planet itself.
0:05:46 > 0:05:49Yet the most sophisticated telescopes couldn't show astronomers
0:05:49 > 0:05:52much about the surface or atmosphere.
0:05:52 > 0:05:54It was just too far away.
0:05:54 > 0:05:58They had to get closer, and that meant going into space.
0:06:00 > 0:06:04By 1959, an unmanned spacecraft had successfully reached the moon.
0:06:04 > 0:06:08But Mars is over a thousand times further away.
0:06:08 > 0:06:10Getting to the Red Planet
0:06:10 > 0:06:14would mean pushing current technology to the limit.
0:06:14 > 0:06:18It is difficult to overstate the extraordinary challenge involved in getting to Mars.
0:06:18 > 0:06:23The moon is only 380,000 kilometres away, but takes nearly three days
0:06:23 > 0:06:27travelling at speeds of up to 40,000 kilometres an hour to reach.
0:06:27 > 0:06:31And missions to Mars make these journeys appear pale in comparison.
0:06:31 > 0:06:35With 450 million kilometres to cross and round trips of more than a year,
0:06:35 > 0:06:40tiny errors in navigation are going to leave you literally lost in space.
0:06:40 > 0:06:43And these aren't the only risks. Space is fraught with hazards.
0:06:43 > 0:06:47Hard vacuum, solar flares, radiation, searing heat, freezing cold,
0:06:47 > 0:06:52all of which can destroy your spacecraft or its delicate electronics.
0:06:52 > 0:06:56If anyone was going to be able to solve the problems of getting to Mars,
0:06:56 > 0:07:00it would be the trail-blazing team at the jet propulsion laboratory,
0:07:00 > 0:07:03who'd been testing and firing rockets since the 1930s.
0:07:11 > 0:07:13Caltech's jet propulsion laboratory,
0:07:13 > 0:07:17the oldest continuous rocket and missile activity in the Western world.
0:07:21 > 0:07:26In this chamber, the spacecraft was subjected to a full spectrum of light
0:07:26 > 0:07:32as intense as the sun's in an environment 300 degrees below zero.
0:07:32 > 0:07:36Here, a technician in protective clothing measures the light intensity.
0:07:38 > 0:07:43Then, in 1964, Mariner 4 was finally ready to launch.
0:07:43 > 0:07:46Horizon took a look behind the scenes.
0:07:47 > 0:07:52While the first man was orbiting the Earth, a spacecraft was being assembled to go to Mars.
0:07:52 > 0:07:57Named Mariner 4, it carried a television camera to transmit live pictures back to earth.
0:07:57 > 0:08:00In November '64 it was launched.
0:08:02 > 0:08:04It was a shot in the dark.
0:08:04 > 0:08:07The best maps available to the space scientists
0:08:07 > 0:08:11were basically 19th-century, rough and ill-defined.
0:08:11 > 0:08:13And yet the journey required incredible precision.
0:08:13 > 0:08:17Mariner 4, travelling more than a million miles a day,
0:08:17 > 0:08:19would take eight months to reach the planet,
0:08:19 > 0:08:23and sweep by only a few thousand miles above the surface.
0:08:23 > 0:08:26And on July 14th they made it.
0:08:26 > 0:08:27CHEERING
0:08:30 > 0:08:34As Mariner 4 swept past Mars, its black and white television camera
0:08:34 > 0:08:37snapped 22 close-up pictures of the planet.
0:08:39 > 0:08:43These images, the first-ever digital television pictures, were stored
0:08:43 > 0:08:48on a tape recorder. Then they had to be radioed back to Earth.
0:08:48 > 0:08:51Would you believe that our bitrates in those days were quite low?
0:08:51 > 0:08:54I think it was 8.3 bits per second,
0:08:54 > 0:08:58a little faster than a pretty good telegrapher can do dots and dashes.
0:08:58 > 0:09:02So the eight bits per second came from Mars, from the spacecraft,
0:09:02 > 0:09:07to the big antenna out in Goldstone antenna range.
0:09:08 > 0:09:10And they were actually teletyped back
0:09:10 > 0:09:14and they came in as little strips of zeros and ones. Incredible.
0:09:15 > 0:09:20Yuri Van der Wood is keeper of JPL's planetary image archive.
0:09:20 > 0:09:25Just outside the office, you will see that here are these little strips.
0:09:25 > 0:09:29And you can see the groups of numbers
0:09:29 > 0:09:35that indicate the strength of the return signal in light and dark.
0:09:35 > 0:09:43As fast as we could staple these little strips on and we could colour them in, we started to see a picture.
0:09:45 > 0:09:48Mariner's first picture shows the lower edge of Mars,
0:09:48 > 0:09:53with the planet in the top of the frame and the black of space below.
0:09:53 > 0:09:58To the old-timers particularly, it is a thing of tremendous value.
0:09:58 > 0:10:02I would almost say I burn candles here at night, you know!
0:10:02 > 0:10:05All the frames as we got them had about as much texture,
0:10:05 > 0:10:07seemingly, to the eye, as this,
0:10:07 > 0:10:10when you just made a Polaroid off the screen.
0:10:10 > 0:10:15But since they were digital, they were computer numbers, we could subtract, and that's what we did.
0:10:21 > 0:10:25But when the images were analysed the dream of finding life on Mars seemed remote.
0:10:25 > 0:10:28Three centuries of exploration
0:10:28 > 0:10:31overturned by a handful of fuzzy pictures.
0:10:31 > 0:10:33Mars wasn't at all like the earth.
0:10:33 > 0:10:35It seemed dead, like the moon.
0:10:37 > 0:10:38The scientists, I think,
0:10:38 > 0:10:41were shocked by seeing large, lunar-like craters.
0:10:41 > 0:10:46The reason is that the craters on the moon had to have formed
0:10:46 > 0:10:49very long ago, the very, very large ones.
0:10:49 > 0:10:51And likewise on Mars.
0:10:51 > 0:10:56And to find them still preserved there meant that the planet had not
0:10:56 > 0:10:59recycled its surface the way the earth does.
0:10:59 > 0:11:02There must have been no rainfall, no weathering,
0:11:02 > 0:11:07no transport in any way comparable to that of the Earth for billions of years
0:11:07 > 0:11:11in order for Mars now, or even parts of it, to resemble the moon.
0:11:16 > 0:11:18In 1969, they tried again,
0:11:18 > 0:11:23sending two spacecraft with more powerful cameras.
0:11:23 > 0:11:27Scientists were hopeful that, although Mars looked like the moon from a distance,
0:11:27 > 0:11:31close-up pictures from Mariner 6 might reveal something unexpected.
0:11:31 > 0:11:36We've just had some amazing photographs sent back by the American probe to Mars, Mariner 6.
0:11:36 > 0:11:37And just look at that!
0:11:37 > 0:11:41Craters on Mars, very similar to those of the moon.
0:11:41 > 0:11:45And the largest crater on that picture is about 160 miles across.
0:11:45 > 0:11:48And remember, when Mariner took that picture, it was only about as far
0:11:48 > 0:11:52from the surface of Mars as we are from Moscow.
0:11:52 > 0:11:54And I wonder how those craters got there. What are they?
0:11:54 > 0:11:58Are they due to things hitting Mars or are they volcanic?
0:11:58 > 0:12:01I believe myself that most of them are likely to be volcanic.
0:12:01 > 0:12:05It was Mars' geology that got space scientists really excited.
0:12:05 > 0:12:08And there was still a hope that, despite appearances,
0:12:08 > 0:12:11conditions on the surface might be suitable for life.
0:12:11 > 0:12:14That's beautiful. That's beautiful. Look at those little craters.
0:12:14 > 0:12:20This is a narrow-angle camera view and the scale...
0:12:20 > 0:12:25on that...is approximately 50 miles across the picture.
0:12:25 > 0:12:29But, besides cameras, the spacecraft carried a battery of instruments.
0:12:29 > 0:12:33They measured the atmosphere and found it was painfully thin.
0:12:33 > 0:12:39A pressure of only seven millibars, 100 times less than Earth, and containing mainly carbon dioxide.
0:12:39 > 0:12:45Temperature readings suggested that the pole caps were not ice but frozen carbon dioxide.
0:12:45 > 0:12:49Mars was even colder and more hostile than we'd thought.
0:12:49 > 0:12:52The scientists were disappointed.
0:12:52 > 0:12:58They might not have found evidence of life, but seeing the surface of Mars up close for the first time
0:12:58 > 0:13:01was a major achievement for the Mariner team.
0:13:01 > 0:13:08While programmes like Horizon reported on the findings, Mars was largely ignored by the public.
0:13:08 > 0:13:12In 1969, they had their eyes firmly set on the moon.
0:13:12 > 0:13:15Two, one, zero.
0:13:17 > 0:13:19We have commencement. We have lift-off.
0:13:33 > 0:13:36We've just heard that all over the world there are
0:13:36 > 0:13:3933 countries who have stayed up to take these pictures live.
0:13:39 > 0:13:44More than half a billion people tuned in to see Aldrin and Armstrong walk on the moon.
0:13:44 > 0:13:48- OK, I'm going to move it.- Roger, we see Buzz going about his work.
0:13:48 > 0:13:53At the time, it was the single most watched live event in history.
0:13:53 > 0:13:57The moon landings are an incredible thing to watch even now,
0:13:57 > 0:14:01but by the time we set foot on the moon we already knew a lot about it.
0:14:01 > 0:14:06To my mind, even more amazing things were being learned about Mars by the Mariner teams.
0:14:09 > 0:14:13But, while Apollo beguiled the public, in the background
0:14:13 > 0:14:18scientists were preparing to try something even more ambitious in scale,
0:14:18 > 0:14:21actually landing on the surface of Mars.
0:14:21 > 0:14:26America may have beaten Russia to put a man on the moon, but the space race hadn't ended there.
0:14:28 > 0:14:31The Soviets already had Mars on their minds.
0:14:31 > 0:14:36They were close to launching a spacecraft that would land on the Red Planet.
0:14:38 > 0:14:43And in 1971, when the probe Mars 3 successfully reached the surface,
0:14:43 > 0:14:45it appeared Russia had won the contest.
0:14:47 > 0:14:49But disaster struck.
0:14:49 > 0:14:53The lander stopped transmitting information back to earth after just 90 seconds.
0:14:58 > 0:15:01Would NASA's attempt fare any better?
0:15:10 > 0:15:13One of the Viking team showed off their design,
0:15:13 > 0:15:15a machine made in the image of man.
0:15:17 > 0:15:20First of all there are two eyes.
0:15:20 > 0:15:23And the eyes are even better than those eyes which a human being has.
0:15:23 > 0:15:29They can see not only in colour, but also in stereo and in the infrared part of the spectrum.
0:15:29 > 0:15:31It has a sense of touch - the meteorology boom.
0:15:31 > 0:15:33It tells it the temperature, whether it's hot or cold,
0:15:33 > 0:15:36the relative humidity and how much the wind is blowing.
0:15:36 > 0:15:39It has an arm so it can extend out into the area around it
0:15:39 > 0:15:43and pick up sand and bring it back to the other laboratories on board the lander.
0:15:43 > 0:15:46It has a sense of hearing, in two different ranges of frequency.
0:15:46 > 0:15:52Then of course it has this fantastic sense of smell which is personified by the organic chemistry experiment.
0:15:52 > 0:15:55This sense of smell is far more powerful than our olfactory
0:15:55 > 0:15:59and can distinguish between the various aromatic compounds which may be in the air.
0:15:59 > 0:16:04But by far the most important feature of the lander is its brain.
0:16:04 > 0:16:06This particular brain of course is a computer.
0:16:06 > 0:16:10It sits down inside the lander, it's roughly the size of a suitcase,
0:16:10 > 0:16:14weighs 52lbs and has a vocabulary of 18,000 words.
0:16:14 > 0:16:17This brain not only controls the lander
0:16:17 > 0:16:21in response to the specific commands that we give it from the Earth, but it makes decisions on its own.
0:16:21 > 0:16:26The lander brain determines its altitude, determines its navigational parameters
0:16:26 > 0:16:31and makes logical selections on such things as when to throw away the heat shield,
0:16:31 > 0:16:35when to pop the parachute and when to turn on the terminal descent engines.
0:16:35 > 0:16:38It is because of these decision-making capabilities
0:16:38 > 0:16:42that the lander truly stands out as a piece of automatic intelligence.
0:16:42 > 0:16:47And because it has this automatic intelligence it has really earned its name of "robot".
0:16:51 > 0:16:54But don't let this simple explanation fool you.
0:16:54 > 0:16:58Building a craft to reach the surface of Mars and operate once there
0:16:58 > 0:17:01was an exceptionally difficult technical challenge.
0:17:03 > 0:17:08Viking was launched in 1975 and made it into Mars' orbit without any hitches.
0:17:12 > 0:17:17As the team gathered for the probe's landing, they knew the final seven minutes of its ten-month journey
0:17:17 > 0:17:20were the hardest part of the mission.
0:17:21 > 0:17:26Viking would have to survive a fiery plunge through the planet's thin atmosphere,
0:17:26 > 0:17:33slowing from a speed of nearly 21,000 kilometres per hour to land safely on the service.
0:17:37 > 0:17:42- 23 Gs.- 2,600ft. - On terminal descent.
0:17:42 > 0:17:441200ft, 140ft per second.
0:17:44 > 0:17:47Coming down...straight down.
0:17:47 > 0:17:50May I have a screen for touchdown?
0:17:50 > 0:17:53..1.5 degrees per second max. 22 Gs.
0:17:53 > 0:17:55Touchdown! We have touchdown!
0:18:09 > 0:18:12And there's the first piece of information coming in.
0:18:15 > 0:18:16Oh... Oh...
0:18:18 > 0:18:19Say something.
0:18:19 > 0:18:22Yeah, I'm supposed to say something at this point.
0:18:22 > 0:18:25I just don't feel like talking!
0:18:25 > 0:18:29- Well, there are rocks.- There are rocks, yes. There's rocks and...
0:18:29 > 0:18:34It's just... Oh, it's just incredible to see that the...
0:18:34 > 0:18:36Mars, you know, is really there.
0:18:36 > 0:18:42Um...instant interpretation is always a little bit hazardous,
0:18:42 > 0:18:45nonetheless many of these boulders
0:18:45 > 0:18:48do look very similar to ones that we've seen in...
0:18:48 > 0:18:50desert terrains here.
0:18:50 > 0:18:54Some of these boulders may be vesicular,
0:18:54 > 0:18:57that is, basalt rocks possibly,
0:18:57 > 0:19:01volcanic rocks that have solidified in a gas-charged environment,
0:19:01 > 0:19:05and these gases produce vesicles, or holes.
0:19:05 > 0:19:10It just looks like a... perfect set down.
0:19:11 > 0:19:14The first picture of the Martian panorama.
0:19:17 > 0:19:20As you look at the field of view in general,
0:19:20 > 0:19:24I think the most striking impression is one of a lot of rocks.
0:19:24 > 0:19:26And this automatically brings to mind
0:19:26 > 0:19:29the fact that we had a good deal of luck,
0:19:29 > 0:19:33because some of these rocks are about two, three metres across,
0:19:33 > 0:19:36and had the spacecraft landed on those rocks
0:19:36 > 0:19:38it would have been disabled.
0:19:38 > 0:19:40Probably permanently disabled.
0:19:42 > 0:19:44Later high-resolution pictures
0:19:44 > 0:19:48confirmed the rocks were volcanic but lying on dunes of fine sand.
0:19:50 > 0:19:54On the second day, the first pictures in colour.
0:19:58 > 0:20:01Mars was indeed the Red Planet.
0:20:01 > 0:20:03Or at any rate, blue-red.
0:20:04 > 0:20:06But the colours were false.
0:20:06 > 0:20:10It was noticed that one of the cables on the space craft wasn't orange enough.
0:20:12 > 0:20:16The colour was corrected and Mars turned even redder.
0:20:20 > 0:20:22The reason for their mistake?
0:20:22 > 0:20:26The sky. Everyone had assumed it would be blue, like on Earth,
0:20:26 > 0:20:31but on Mars scattered dust turns the sky pink and makes sunsets purple.
0:20:33 > 0:20:36But they weren't just there for the scenery.
0:20:36 > 0:20:40It was time to answer the question of whether there was life on Mars.
0:20:40 > 0:20:44By the morning of the eighth day the arm had taken its first soil sample.
0:20:44 > 0:20:50There was a clear trench on the surface and the biological laboratories returned their analyses.
0:20:56 > 0:20:58Across 200 million miles of space
0:20:58 > 0:21:03came the message that was hoped to end three centuries of speculation.
0:21:10 > 0:21:14These traces were to be the final arbiters of life on Mars.
0:21:16 > 0:21:21They came from a machine on the lander that could make a detailed analysis of the soil.
0:21:21 > 0:21:26Technically, it was a gas chromatograph mass spectrometer, a miracle of miniaturisation.
0:21:26 > 0:21:30It could sniff out what molecules were present in the soil.
0:21:32 > 0:21:37Its life-detecting task was to search for organic matter in the soil of Mars
0:21:37 > 0:21:41by analysing what gases the soil gave off when it was heated,
0:21:41 > 0:21:44in a tiny oven the size of a matchbox.
0:21:47 > 0:21:52Within a few weeks the instrument on Mars had produced a complete fingerprint of the soil.
0:21:52 > 0:21:55At first, it looked Earth-like.
0:21:55 > 0:21:59There was nitrogen, carbon dioxide, argon and traces of oxygen and water.
0:21:59 > 0:22:04But on Earth the heavier molecules of living systems would show further down the chart.
0:22:04 > 0:22:07And on Mars the peaks weren't there.
0:22:09 > 0:22:12For the biologists it was a bombshell.
0:22:14 > 0:22:19Their tests had said life, and yet life without organic matter was unheard of.
0:22:19 > 0:22:22So, some questioned the spectrometer's sensitivity.
0:22:22 > 0:22:26Others speculated about cannibal micro-organisms
0:22:26 > 0:22:30that lived by consuming their own organic debris.
0:22:30 > 0:22:32The scientists couldn't explain it.
0:22:32 > 0:22:37The Martian soil was active in the instruments on the lander, but there was no organic matter.
0:22:38 > 0:22:42The building blocks for life were there, but life itself wasn't.
0:22:44 > 0:22:47Unfortunately, even the tantalising nature of these results
0:22:47 > 0:22:52wasn't enough to persuade politicians to support another trip to the Red Planet.
0:22:53 > 0:22:57In fact, it was to be 17 years before we would go back to Mars.
0:23:01 > 0:23:06And then, in 1992, a new era of Mars exploration began
0:23:06 > 0:23:09with the launch of Mars Observer.
0:23:10 > 0:23:11We have lift-off!
0:23:11 > 0:23:15Lift off of the Type-3 rocket with the Mars Observer
0:23:15 > 0:23:18and America's return to the Red Planet.
0:23:18 > 0:23:24I believe that before Apollo celebrates the 50th anniversary
0:23:24 > 0:23:29of its landing on the moon, the American flag should be planted on Mars.
0:23:30 > 0:23:34Observer was the first of five US missions to Mars in the 1990s.
0:23:34 > 0:23:37The Red Planet was very much back on the agenda.
0:23:37 > 0:23:41And we have lift-off of NASA's Mars Global surveyor,
0:23:41 > 0:23:45as America begins its journey back to the Red Planet.
0:23:45 > 0:23:50But, despite their high hopes, more than half of NASA's missions to Mars that decade failed.
0:23:53 > 0:23:58Now, it's a mistake many of us have made, but then most of us aren't in charge of missions into space.
0:23:58 > 0:24:03Scientists at NASA couldn't work out why the Mars Orbiter, worth a small £78 million,
0:24:03 > 0:24:09got lost in space, until someone pointed out that they'd planned everything in feet and inches
0:24:09 > 0:24:11rather than metres and centimetres.
0:24:11 > 0:24:16Eight days ago, as it approached the Red Planet, contact with the craft was lost.
0:24:16 > 0:24:22This was the moment when NASA scientists realised something had gone horribly wrong.
0:24:22 > 0:24:27The American space agency NASA is on the verge of having to admit to another embarrassing failure.
0:24:27 > 0:24:32The Mars Polar Lander would be the second spacecraft that it's lost in just two months.
0:24:32 > 0:24:37And there's still no convincing explanation for what might have gone wrong.
0:24:37 > 0:24:40The strain is starting to show.
0:24:40 > 0:24:43Three days on, and still no sign of their lost lander.
0:24:43 > 0:24:49NASA engineers had thought it was just a case of a misdirected communications antenna.
0:24:49 > 0:24:54Now it looks likely that the spacecraft could be seriously damaged.
0:24:55 > 0:24:59Thousands of functions are performed during a space mission.
0:24:59 > 0:25:02Just one man-made mistake can be catastrophic.
0:25:02 > 0:25:04These failures were a timely reminder.
0:25:04 > 0:25:08Crossing millions of miles with pinpoint accuracy, and withstanding
0:25:08 > 0:25:13the rigours of space to reach Mars, were an extraordinary challenge for a spacecraft and its operators.
0:25:13 > 0:25:16Success was never guaranteed.
0:25:18 > 0:25:22Faced with the technical difficulties of even reaching Mars, the prospect of actually
0:25:22 > 0:25:26finding life on the Red Planet was beginning to seem unrealistic.
0:25:28 > 0:25:31But then a breakthrough came from an unexpected place.
0:25:33 > 0:25:37Here, on Earth, geologists had been investigating Martian meteorites
0:25:37 > 0:25:41in the hope they might reveal more about the Red Planet.
0:25:41 > 0:25:44And they found something incredible.
0:25:44 > 0:25:51For the first time in human history, evidence has been discovered of life on another planet.
0:25:51 > 0:25:54The announcement was made by American scientists late last night.
0:25:54 > 0:25:59A spokesman for the US space agency, NASA, called it a startling discovery.
0:25:59 > 0:26:01MUSIC: "Life On Mars" by David Bowie
0:26:12 > 0:26:19We have a number of forms, which is very tempting for us to interpret as Martian micro-fossils.
0:26:19 > 0:26:23Today, rock 84001 speaks to us
0:26:23 > 0:26:28across all those billions of years and millions of miles.
0:26:28 > 0:26:32If this discovery is confirmed, it will surely be one of the most
0:26:32 > 0:26:36stunning insights into our universe that science has ever uncovered.
0:26:39 > 0:26:43The usually sober Horizon got swept up in the story.
0:26:43 > 0:26:47It devoted a whole programme to NASA's announcement
0:26:47 > 0:26:52that they thought they'd discovered Martian life in a meteorite.
0:26:52 > 0:26:56The unlikely location of this discovery was Antarctica.
0:26:58 > 0:27:04Each summer, a US expedition heads south to hunt for meteorites.
0:27:04 > 0:27:06It's led by Ralph Harvey.
0:27:06 > 0:27:11If you wanna go somewhere on Earth where the rocks you find must have
0:27:11 > 0:27:18fallen from the sky, you go to a place where there's a great natural white sheet on the ground.
0:27:18 > 0:27:19Antarctica is perfect for that.
0:27:21 > 0:27:27Any rock you find at the top of 10,000 ft pile of ice and snow had to have fallen there from the sky.
0:27:30 > 0:27:33When you find a meteorite, it's just really exciting.
0:27:33 > 0:27:38You can go for hours and nobody will find a meteorite, and all of a sudden you run into one.
0:27:38 > 0:27:40It's a break, so everybody gets together.
0:27:42 > 0:27:44Yeah, another one.
0:27:46 > 0:27:48OK...
0:27:50 > 0:27:52We ran into the rock.
0:27:52 > 0:27:56I remember it was bigger than other rocks we had been collecting.
0:27:56 > 0:27:59Because of the brightness of the area, and the colour of the snow
0:27:59 > 0:28:03and ice, and the dark glasses, it had a very green tint to me.
0:28:03 > 0:28:09And we were all excited for being in this beautiful area and finding this green rock.
0:28:09 > 0:28:11It just really stood out in my mind.
0:28:11 > 0:28:12I even wrote it down in my journal.
0:28:18 > 0:28:25At the end of the season, the find was shipped back to Houston, to NASA's Johnson Space Centre.
0:28:25 > 0:28:29Meteorites are named after local post offices where they fell,
0:28:29 > 0:28:33and obviously there's no post offices in Antarctica.
0:28:33 > 0:28:35So we named them after the local features.
0:28:35 > 0:28:37And ALH stands for Alan Hills.
0:28:37 > 0:28:3984 is the year it was collected.
0:28:39 > 0:28:43And 01 was the first lab number we pulled out.
0:28:47 > 0:28:51Once in the lab, the rock was photographed, described and catalogued,
0:28:51 > 0:28:56then put into storage among all the others waiting to be studied by scientists around the world.
0:28:56 > 0:29:00The true nature of this meteorite was nearly lost to science forever.
0:29:00 > 0:29:05Unfortunately, 8401 was misclassified as a rock like this.
0:29:05 > 0:29:07This is a diogenite.
0:29:07 > 0:29:12It's a coarsely crystalline rock from the asteroid belt.
0:29:12 > 0:29:16And so 8401 lived its life for 10 years
0:29:16 > 0:29:21in a curation facility at the Johnson Space Centre
0:29:21 > 0:29:24under the label of diogenite,
0:29:24 > 0:29:30until Dave Mittelfeld requested a specimen as part of his study of diogenites.
0:29:30 > 0:29:35And then when he looked at 8401, he realised it wasn't a diogenite,
0:29:35 > 0:29:39but in fact, was a member of a small group of meteorites,
0:29:39 > 0:29:42rather like this one.
0:29:42 > 0:29:47This rock is one of a small group that are very special indeed.
0:29:47 > 0:29:55They have come to us not from the asteroid belt, but from our neighbouring planet, from Mars.
0:29:57 > 0:30:05Scientists studied this piece of the Red Planet in microscopic detail, and found something extraordinary.
0:30:05 > 0:30:12This is one thousandth of the width of a human hair, so these are extremely tiny things.
0:30:18 > 0:30:22One evening, we were moving around and we came across a region
0:30:22 > 0:30:26that appeared to be a little different from what we had normally seen.
0:30:26 > 0:30:32And we kept scanning in at higher magnification,
0:30:32 > 0:30:35and we saw something that caught our eye.
0:30:40 > 0:30:43And we said, "What is that?"
0:30:43 > 0:30:46We found this structure.
0:30:46 > 0:30:53It had 10 to 12 segments in it. And appeared to have a head and a tail.
0:30:53 > 0:30:56And we looked at each other
0:30:56 > 0:31:00with a look that kinda said, "This can't be."
0:31:00 > 0:31:05And the significance of the structure got to both of us.
0:31:05 > 0:31:10I went home and that night, I had difficulty sleeping.
0:31:10 > 0:31:15I was saying, "Could we have a micro-fossil here from Mars?"
0:31:22 > 0:31:29If it can be established that life has arisen on Mars quite independently of Earth,
0:31:29 > 0:31:32then in my view that would be a discovery more profound
0:31:32 > 0:31:36than the work of Copernicus and Darwin and Einstein put together.
0:31:36 > 0:31:40It would truly be the most amazing scientific discovery of all time.
0:31:40 > 0:31:44NASA scientists believed they'd solved the centuries-old mystery
0:31:44 > 0:31:47of whether life had evolved on other planets.
0:31:47 > 0:31:52If our evidence continues to pan out, which we think it will,
0:31:52 > 0:31:59it will show for the first time that we are not alone in this giant universe that we live in.
0:32:04 > 0:32:07My first trip to NASA was shortly after this discovery.
0:32:07 > 0:32:09The place was alive with anticipation.
0:32:09 > 0:32:13People were wandering around wearing badges saying, "Mars or Bust".
0:32:13 > 0:32:18But the excitement was short lived. Each of the lines of evidence that pointed towards
0:32:18 > 0:32:21fossilised Martian life could be explained in other ways.
0:32:21 > 0:32:24Scientists found that the organic material
0:32:24 > 0:32:28in the meteorite could have been created by non-biological processes.
0:32:28 > 0:32:33Or even be the result of contamination from Antarctic ice.
0:32:33 > 0:32:35The scientific community was divided.
0:32:35 > 0:32:40The only way to know if there had ever been life on Mars was to go back.
0:32:49 > 0:32:53Despite the loss of several missions to the Red Planet in the 1990s,
0:32:53 > 0:32:57scientists were determined to try and get to Mars once more.
0:32:57 > 0:33:01And this time they had the search for life at the very heart of their operation.
0:33:08 > 0:33:12The search for life is the search for liquid water.
0:33:14 > 0:33:17Life on Earth is basically full of water.
0:33:17 > 0:33:21Life forms are basically little bags of water with a few other ingredients added.
0:33:21 > 0:33:23But water is the main component.
0:33:23 > 0:33:25Water is what makes it work.
0:33:32 > 0:33:34On Earth, all life is based on water.
0:33:34 > 0:33:38It's the main constituent of every cell.
0:33:40 > 0:33:45Because water is basically inert, it's the perfect medium for different types of molecules
0:33:45 > 0:33:48to flow around, meet and react together.
0:33:53 > 0:33:56It enables life to form.
0:33:59 > 0:34:04Horizon took a look at NASA's attempts to find water on Mars.
0:34:04 > 0:34:08When we look at the history of life on Earth, it appears to start very quickly.
0:34:08 > 0:34:10Maybe a hundred million years.
0:34:10 > 0:34:13That seems like a long time, but for a planet that's short.
0:34:13 > 0:34:17So if there was water on Mars for a couple of hundred million years,
0:34:17 > 0:34:19then life had a good shot at getting started there.
0:34:24 > 0:34:29And soon they found evidence the water had been there for millions of years.
0:34:42 > 0:34:45It was all because of one very important picture.
0:34:47 > 0:34:53Sent back in December 2000, it was of vast formations of sedimentary rock.
0:34:55 > 0:34:58Sediment is basically made of sand.
0:34:58 > 0:35:04It can only have been deposited over millions of years by a huge body of water like a lake or an ocean.
0:35:07 > 0:35:10It showed that not only had there been masses of water,
0:35:10 > 0:35:14but it had been around long enough for life to form.
0:35:17 > 0:35:20The sediments on the surface were now dry and exposed.
0:35:20 > 0:35:24If they ever had contained life, it could not possibly have survived.
0:35:27 > 0:35:33However, scientists hoped that microbes deeper down might still be alive, frozen in the ground.
0:35:37 > 0:35:42To find the actual organic remains of a Martian organism, we're gonna need to go to frozen material.
0:35:44 > 0:35:50In the ice, life might have been preserved, frozen in a state of suspended animation.
0:35:56 > 0:36:03No-one at this stage could know if microbes formed millions of years ago could have survived on Mars.
0:36:03 > 0:36:07But there were indications that it really was possible.
0:36:11 > 0:36:15Once again it was Earth that would hold the key to life on Mars.
0:36:17 > 0:36:21Antarctica, the closest place on Earth to conditions on Mars.
0:36:23 > 0:36:30Until a few years ago, no-one thought life could survive being deep frozen for millions of years.
0:36:30 > 0:36:32But research here has helped change that.
0:36:36 > 0:36:41The ground here is permafrost, a mixture of soil and ice frozen together.
0:36:44 > 0:36:49A group of Russian scientists teamed up with NASA to drill down into it in search of micro-organisms.
0:36:53 > 0:36:58They drilled so deep, they reached permafrost laid down millions of years ago.
0:37:02 > 0:37:05The frozen cores were taken back to their laboratory.
0:37:05 > 0:37:10Samples were taken from the centre of the core, then they looked for signs of life.
0:37:23 > 0:37:26They discovered that bacteria can survive in the permafrost
0:37:26 > 0:37:29for far longer than anyone had thought possible.
0:37:42 > 0:37:48They found bacteria that may turn out to have been at -20 degrees for more than 10 million years.
0:37:50 > 0:37:56Probably we have now these bacteria from Antarctic permafrost
0:37:56 > 0:37:59between eight and 15 million years old.
0:38:01 > 0:38:08Bacteria had been buried alive here in frozen ground since the beginning of human evolution.
0:38:08 > 0:38:12If life can survive in Antarctica for 15 million years,
0:38:12 > 0:38:16then something could be waiting to be revived on Mars.
0:38:20 > 0:38:24These discoveries put new urgency into the quest to find water on Mars.
0:38:24 > 0:38:29There was now a real possibility they might find something alive.
0:38:40 > 0:38:45But scientists needed little reminder that getting to Mars would be hazardous.
0:38:45 > 0:38:47Professor of Cosmo-Chemistry, William Boynton,
0:38:47 > 0:38:51had lost precious equipment on two of the botched missions.
0:38:51 > 0:38:54But he decided to try one more time.
0:38:55 > 0:38:59This was really my third attempt to get to Mars.
0:38:59 > 0:39:02Some of my colleagues said, "Bill, are you crazy?
0:39:02 > 0:39:04"You're doing this a third time?"
0:39:04 > 0:39:06"Why are you putting so much time in on this?"
0:39:06 > 0:39:08And I just couldn't say no.
0:39:08 > 0:39:12I think there was just a calling that I had to go back.
0:39:15 > 0:39:18We have a device called a gamma ray spectrometer.
0:39:18 > 0:39:25It's designed to determine what elements are present on Mars that make up the surface.
0:39:25 > 0:39:28And probably the most important one of those is hydrogen,
0:39:28 > 0:39:31because that's the main constituent element in water.
0:39:34 > 0:39:37VOICEOVER: "We have ignition and lift-off
0:39:37 > 0:39:41"of a Delta Two rocket carrying NASA on an odyssey back to Mars."
0:39:41 > 0:39:48On 7th April 2001, NASA launched Odyssey, carrying Boynton's device.
0:39:48 > 0:39:51This time, everything went according to plan.
0:39:56 > 0:39:58One, two, set.
0:39:58 > 0:40:02We are separating the stages.
0:40:02 > 0:40:04Second-stage ignition.
0:40:11 > 0:40:16Once in Mars' orbit, the instrument was deployed.
0:40:16 > 0:40:19The gamma-ray detector could get to work.
0:40:27 > 0:40:31The data was radioed back from Odyssey to NASA
0:40:31 > 0:40:36to the University of Tucson and finally to Boynton's desk.
0:40:39 > 0:40:42As the data came through, a picture started to build.
0:40:46 > 0:40:52When I first saw the signal, I was looking through it and first trying to find the hydrogen signal.
0:40:52 > 0:40:55When I saw it, it was so big I couldn't believe it.
0:40:55 > 0:41:01I actually had to do some checks to see, could this be real or somehow did we mess things up?
0:41:14 > 0:41:20It could only mean one thing - there is water ice on Mars today, and there is masses of it.
0:41:23 > 0:41:26Boynton and his team had discovered a vast ocean
0:41:26 > 0:41:31in the southern hemisphere, a frozen ocean over 5,000 kilometres wide.
0:41:34 > 0:41:36What we found is, just in the surface,
0:41:36 > 0:41:41if we melted that would be enough to fill Lake Michigan two times over.
0:41:41 > 0:41:45There is probably a lot more, because we don't know how deep the ice goes.
0:41:45 > 0:41:47That is just in the upper metre.
0:41:47 > 0:41:51It could be 10 metres deep, it could be 100 metres deep.
0:41:51 > 0:41:53There's a lot of ice there.
0:41:53 > 0:41:59The ice they found is trapped in the ground, a permafrost, just like in Antarctica.
0:42:01 > 0:42:03It was a smoking gun.
0:42:03 > 0:42:06They'd found the one thing needed for life to evolve.
0:42:06 > 0:42:10But the question of whether life was actually there remained unanswered.
0:42:20 > 0:42:25In 2003, it was Britain's turn to join the race to find life on the Red Planet.
0:42:25 > 0:42:29Beagle 2 was a lander, carrying scientific instruments designed
0:42:29 > 0:42:34to search for carbon - something which exists in all living things.
0:42:34 > 0:42:38It was also equipped with an ingenious device called a mole,
0:42:38 > 0:42:41which could take samples under rocks around the landing site
0:42:41 > 0:42:46in the previously inaccessible places scientists thought life most likely to survive.
0:42:47 > 0:42:53After travelling 400 million kilometres, Mars Express, Europe's first Mars rocket,
0:42:53 > 0:42:57arrived safely to the planet with Beagle 2 onboard.
0:42:59 > 0:43:02On Christmas Day 2003, the lander began its hazardous
0:43:02 > 0:43:06seven-minute journey through the atmosphere to the surface.
0:43:06 > 0:43:10Mission scientists awaited news of Beagle's expected touchdown.
0:43:10 > 0:43:14With national pride at stake, Britain took notice.
0:43:14 > 0:43:18Good morning. Welcome to Breakfast from BBC News with Bill Turnbull.
0:43:18 > 0:43:26No message from Mars - scientists fail to make contact with the Beagle 2 probe but say all is not yet lost.
0:43:26 > 0:43:29That's our main story on Christmas Day, 25th December.
0:43:29 > 0:43:33It was a long, tense wait through the night.
0:43:33 > 0:43:36Would Britain's first mission to another planet actually make it?
0:43:36 > 0:43:42Before dawn, the mastermind of the project, Colin Pillinger, was on the line to NASA,
0:43:42 > 0:43:48in the hope that one of its spacecraft had picked up the first signal. It didn't.
0:43:48 > 0:43:53I'm afraid it's a bit disappointing, but it's not the end of the world.
0:43:53 > 0:43:57Please don't go away from here believing
0:43:57 > 0:43:59that we've lost this spacecraft.
0:43:59 > 0:44:04Over the next few days, the British public waited to hear from Beagle,
0:44:04 > 0:44:07but, sadly, the news didn't improve.
0:44:07 > 0:44:10British scientists behind the Beagle 2 mission to Mars
0:44:10 > 0:44:12are refusing to give up hope,
0:44:12 > 0:44:15despite no signal from the probe for more than 24 hours.
0:44:15 > 0:44:19'This morning, the mood among the scientists involved was getting grimmer,
0:44:19 > 0:44:21'but no talk yet of giving up.'
0:44:21 > 0:44:25On this mission, our faith has been unshakeable that the mission would go ahead.
0:44:25 > 0:44:29We've crossed lots of bridges to get this far.
0:44:29 > 0:44:33We'll keep the unshakeable faith until the point comes
0:44:33 > 0:44:37when we have to say that it's no longer worth thinking about.
0:44:37 > 0:44:40British scientists have again failed to make contact
0:44:40 > 0:44:41with the Beagle 2 spacecraft.
0:44:41 > 0:44:43It was their fifth attempt to get in touch.
0:44:43 > 0:44:46'Another frustrating day.
0:44:46 > 0:44:51'Three more attempts to find Beagle overnight, and three more failures.'
0:44:51 > 0:44:54And ten days later, they were forced to admit defeat.
0:44:54 > 0:44:57It looks after all as if the Beagle may have crash-landed.
0:44:57 > 0:45:00Scientists said today that their best chance yet
0:45:00 > 0:45:03to make contact with the British spacecraft has failed.
0:45:03 > 0:45:07'For Colin Pillinger, the man behind Beagle 2,
0:45:07 > 0:45:09'the disappointment was clearly visible.
0:45:09 > 0:45:13'But he remained upbeat about its achievements.'
0:45:13 > 0:45:17Come on, guys, this isn't gonna be a great British failure.
0:45:17 > 0:45:20We have learnt so much that we have to build on this,
0:45:20 > 0:45:26and the lesson that we have to learn is to go forward and have another Beagle.
0:45:26 > 0:45:29The same name is good enough for us.
0:45:29 > 0:45:31It's got us this far. Let's take it on.
0:45:38 > 0:45:43The Americans, meanwhile, were hopeful that they'd have more luck with rovers.
0:45:43 > 0:45:47Rovers are robotic geologists that travel across the surface of a planet.
0:45:47 > 0:45:53Being mobile means that if they see an interesting feature, they can go an investigate it.
0:45:53 > 0:45:55Rovers in all shapes and sizes
0:45:55 > 0:45:58are now being created to go to the Red Planet.
0:45:58 > 0:46:02Horizon investigated their effectiveness.
0:46:02 > 0:46:04'Many could be seen strutting their stuff
0:46:04 > 0:46:08'at a conference of rover designers held on a Californian beach.'
0:46:08 > 0:46:10There are so few rocks that are small,
0:46:10 > 0:46:13that are seen in those two landing sites,
0:46:13 > 0:46:16that in fact this rover, it turns out, can go between the big rocks...
0:46:16 > 0:46:20'There were rovers from Europe, Russia and Japan.'
0:46:20 > 0:46:22It is a big space company...
0:46:27 > 0:46:33Amidst all the enthusiasm for robotic exploration, there was also one voice of caution.
0:46:33 > 0:46:36..Primarily the difference between this Marsokhod
0:46:36 > 0:46:38and the one that you just saw.
0:46:38 > 0:46:43Carol Stoker is working on the robotic exploration of Mars at NASA's Ames Research Center.
0:46:43 > 0:46:49She is an exobiologist, an expert on how to search for life on other worlds.
0:46:49 > 0:46:54I think it is going to be extremely difficult to find fossil life on Mars.
0:46:54 > 0:46:57It's a very tough problem to find it on Earth.
0:46:57 > 0:47:00Any viewer would know from their own experience
0:47:00 > 0:47:05that if they just walked out in their back yard - did they find a fossil there?
0:47:05 > 0:47:06It's not an easy problem.
0:47:06 > 0:47:11To test the effectiveness of robot exploration,
0:47:11 > 0:47:14Carol Stoker has been working with a Russian Marsokhod rover
0:47:14 > 0:47:17to see if it can discover life on Earth.
0:47:17 > 0:47:18INDISTINCT
0:47:18 > 0:47:23'My programme at NASA Ames did a field experiment
0:47:23 > 0:47:29'where we took a science team, actually gave the science team exposure to data from a rover
0:47:29 > 0:47:33'that was placed in a very fossil-rich field site.'
0:47:33 > 0:47:37And how well did the science team do?
0:47:37 > 0:47:40Perhaps they overlooked the odd microscopic fossil?
0:47:40 > 0:47:43No, they were missing very obvious things!
0:47:43 > 0:47:47They were missing dinosaur tracks the size of dinner plates.
0:47:48 > 0:47:51It is an issue of, exactly where do you look?
0:47:51 > 0:47:54'You can be six inches to the left of where the fossil is.
0:47:54 > 0:47:59'If you are not looking right at it, you won't see it. That's the problem with a rover -
0:47:59 > 0:48:03'it's only going to look where you tell it to look.
0:48:04 > 0:48:09'Actually, I think that our best chances of finding evidence of life on Mars'
0:48:09 > 0:48:11is to send human crews. There is no question
0:48:11 > 0:48:16Human crews will do a better job than all the robotics technology we can develop in the next 30 years,
0:48:16 > 0:48:19even if we spend the entire NASA budget on it.
0:48:19 > 0:48:23After 40 years of exploration, evidence that life exists on Mars,
0:48:23 > 0:48:28or has ever been present, seems tantalisingly close but frustratingly just out of reach.
0:48:28 > 0:48:32If we are ever to find the answer to this fundamental question,
0:48:32 > 0:48:34we are going to have to send people to the surface.
0:48:34 > 0:48:39That is going to require tremendous human endeavour before we have even got off the ground.
0:48:46 > 0:48:49When we do send people to Mars,
0:48:49 > 0:48:53it will be one of the most challenging trips humanity has ever undertaken,
0:48:53 > 0:48:58travelling more than 80 million kilometres across the Solar System.
0:49:02 > 0:49:04Robots may have made the trip,
0:49:04 > 0:49:09but sending humans will stretch technological expertise to the limit.
0:49:12 > 0:49:15And it will stretch humans to the limit too.
0:49:15 > 0:49:17Crew members aboard a Mars mission
0:49:17 > 0:49:20will have to endure six months of isolation
0:49:20 > 0:49:22before they even get to the Red Planet.
0:49:22 > 0:49:26Horizon took a look at some of the issues involved.
0:49:26 > 0:49:32'A few days into the flight, the lack of gravity itself will start to affect the crew.
0:49:32 > 0:49:36'The journey to Mars will be a biological battle for survival.
0:49:38 > 0:49:40'As well as all their experience in space,
0:49:40 > 0:49:43'the Russians have a history of ground-based research
0:49:43 > 0:49:47'into the long-term damage that space does to the body.
0:49:47 > 0:49:52'This volunteer has been in bed for a year.
0:49:59 > 0:50:03'Just as would happen in space, with no stress on his body,
0:50:03 > 0:50:07'he is suffering bone loss, and his muscles have been wasting away.
0:50:07 > 0:50:09'His heart capacity has shrunk.
0:50:09 > 0:50:12'Even short bouts of exercise are now exhausting.
0:50:15 > 0:50:21'Until Dr Valery Polyakov completed a world-record 14 months' space flight two years ago,
0:50:21 > 0:50:27'no-one was sure humans could survive the complete return journey to Mars.
0:50:27 > 0:50:33'The aim of this bed-rest research is to develop exercises
0:50:33 > 0:50:38'to prevent bodies designed for life on Earth from slowly decaying in space.
0:50:40 > 0:50:43'From the Russians' experience on Mir,
0:50:43 > 0:50:46'life in space will be dominated by exercise -
0:50:46 > 0:50:51'two hours a day, every day, doing a cosmic workout.
0:51:04 > 0:51:10'Norm Thagard was the first American astronaut to try out the Russians' regime.
0:51:10 > 0:51:13'As a practical matter, you cannot exercise enough
0:51:13 > 0:51:18'to maintain the same fitness level that you would have had had you remained on Earth.'
0:51:18 > 0:51:23Not everyone, even on that regimen, can stand up and walk immediately after returning to Earth.
0:51:23 > 0:51:26Mars' gravity is lower than Earth's gravity,
0:51:26 > 0:51:30so the amount of physical conditioning you would need would be less,
0:51:30 > 0:51:32but you would still need some.
0:51:32 > 0:51:35You wouldn't want to go off to Mars with no exercise at all
0:51:35 > 0:51:40and then expect to be able to perform useful work after landing on the surface of the planet.
0:51:43 > 0:51:46Then there's the small matter of food.
0:52:11 > 0:52:16Anything any astronaut has ever eaten in space began its life on Earth.
0:52:17 > 0:52:22But rather than carrying vast stores of pre-packaged food with them,
0:52:22 > 0:52:26for the long trip to Mars, the crew might grow their own.
0:52:27 > 0:52:31Ground experiments are going on to squeeze every ounce of matter
0:52:31 > 0:52:34from the tiny greenhouse they'd have on the rocket.
0:52:34 > 0:52:40Plants will grow without gravity, but keeping them alive is complicated.
0:52:41 > 0:52:47On their space station Mir, the Russians have slowly been learning about horticulture in space.
0:52:48 > 0:52:54Some plants flown up from Earth do very well, but starting from seeds is much harder.
0:52:54 > 0:53:00Up on Mir now, astronaut Mike Foal is trying to grow rape seedlings.
0:53:00 > 0:53:04They're confused. They don't know which way to grow, cos there's no gravity here,
0:53:04 > 0:53:09so we've been using strong lights above, because they are attracted to the light.
0:53:09 > 0:53:12They will grow up in a month. They'll flower in about two weeks.
0:53:12 > 0:53:15I then have to take bee sticks - pieces of bees on sticks -
0:53:15 > 0:53:18and I go around the flowers and pollinate them.
0:53:18 > 0:53:23They will produce seeds in a month. I will harvest the seeds and keep planting them.
0:53:23 > 0:53:26I'm gonna try and plant three generations of seeds,
0:53:26 > 0:53:29starting with Earth seeds, going to space seeds.
0:53:29 > 0:53:33We have never produced seeds in space that we could plant - never!
0:53:33 > 0:53:37We're that far behind on just getting basic life support going in space.
0:53:37 > 0:53:40We will need vegetables wherever we're going.
0:53:40 > 0:53:43We will need these things, and animals and the rest,
0:53:43 > 0:53:46and the micro-organisms that make up an ecological system.
0:53:58 > 0:54:02When the Russians first tried rearing Japanese quail chicks on Mir,
0:54:02 > 0:54:07the baby birds wouldn't grab hold of anything, so they couldn't feed.
0:54:13 > 0:54:17The solution is to fit the birds with harnesses to anchor them down.
0:54:17 > 0:54:21It seems they then develop normally.
0:54:21 > 0:54:26And the Russians believe quail will make an excellent compact food source in zero gravity.
0:54:26 > 0:54:31But so far, no-one has persuaded them to breed or lay eggs.
0:54:35 > 0:54:38And when we reach Mars, there'll be no relief.
0:54:38 > 0:54:41The average temperature is minus 50 degrees centigrade,
0:54:41 > 0:54:45and it goes down from there to minus 225 degrees at the poles.
0:54:48 > 0:54:54The atmosphere is extremely thin and it's almost all carbon dioxide, and there are frequent dust storms.
0:54:54 > 0:54:57We won't be able to live under open skies.
0:54:57 > 0:55:01We know that conditions on Mars today are not very good for life.
0:55:01 > 0:55:04If you were to go out onto Mars without a spacesuit,
0:55:04 > 0:55:06and I don't recommend it, but if you were,
0:55:06 > 0:55:09your body fluids would literally start to boil,
0:55:09 > 0:55:14because the vapour pressure on Mars is lower than the boiling point of water at body temperature.
0:55:14 > 0:55:19So this would not be a good thing in terms of your ears, eyes, nose and throat.
0:55:19 > 0:55:23You would quickly suffocate and essentially drown in your own bodily fluid.
0:55:26 > 0:55:28We will have to live inside.
0:55:30 > 0:55:35Ground-based experiments that simulate what a life would be like in a Mars colony
0:55:35 > 0:55:39are currently being carried out by the European Space Agency.
0:55:39 > 0:55:45This year, a crew of six were successfully sealed inside a habitat in Moscow for 105 days.
0:55:45 > 0:55:48Now I am ready to go to bed.
0:55:48 > 0:55:52And in 2010, a new mission will run, for 520 days,
0:55:52 > 0:55:55the length of a return trip to Mars,
0:55:55 > 0:55:58plus a 30-day stopover on the surface.
0:55:59 > 0:56:02Despite the challenges we must overcome,
0:56:02 > 0:56:05astronomers think it's inevitable that we will go and live on Mars.
0:56:07 > 0:56:11It's the only planet out there where one can reasonably expect
0:56:11 > 0:56:16that humans could go and establish themselves permanently,
0:56:16 > 0:56:17for what ever reason.
0:56:17 > 0:56:19People could go and live on Mars.
0:56:19 > 0:56:23They can't go and live on Jupiter, but they can go and live on Mars.
0:56:23 > 0:56:26I think just because it's available,
0:56:26 > 0:56:30almost, we have the capacity to go there already,
0:56:30 > 0:56:32that it's inevitable that we will go.
0:56:48 > 0:56:52Mars was the first planet we flew by, orbited, landed on and roved upon.
0:56:52 > 0:56:55It will be the first planet that humans step foot upon.
0:56:55 > 0:56:58When that might happen, is anybody's guess.
0:56:58 > 0:57:03As the United States pulls back from its commitments to reach that planet by 2050,
0:57:03 > 0:57:05one of the greatest thinkers of our generation
0:57:05 > 0:57:10believes the exploration of Mars and the space beyond should be a priority for humankind.
0:57:42 > 0:57:4740 years ago, the best scientific minds believed Mars was similar enough to Earth,
0:57:47 > 0:57:50that they would find life there.
0:57:50 > 0:57:54Then all their hopes and dreams were dashed.
0:57:54 > 0:57:56With each new mission to the Red Planet,
0:57:56 > 0:57:59scientists are discovering reasons to keep looking,
0:57:59 > 0:58:03all in the hope that, one day, we will finally find proof
0:58:03 > 0:58:06that we are not alone in the universe.
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